High-efficiency vertical screw-feeder press for dehydrating liquid-containing products

Abstract

 A high-efficiency vertical screw-feeder press (1) for dehydrating liquid-containing products, comprising an enclosure (3) which is composed of two side-by-side portions (4, 5) which form two substantially conical surfaces which have vertical axes and mutually intersect with their mutually facing regions. Each one of the two portions (4, 5) of the enclosure (3) coaxially accommodates a substantially frustum-shaped shaft (6, 7) which has, on its lateral surface, a screw (8, 9) which is inscribed in the corresponding portion of the enclosure (3) and protrudes, with its turns, between the turns of the screw of the contiguous shaft. The enclosure (3) has, proximate to the larger-diameter end of the two portions (4, 5), an inlet (10) for introducing products to be dehydrated and, proximate to the opposite end, at least one outlet (11) for discharging the dehydrated product.

Description

[0001] The present invention relates to a high-efficiency vertical screw-feeder press for dehydrating liquid-containing products.

[0002] Presses are known for dehydrating by pressing liquid-containing products such as for example waste pulps, which are a byproduct of the processing of sugar beet; such presses are substantially constituted by an enclosure composed of two side-by-side portions which form two conical surfaces which have horizontal axes and mutually intersect with their mutually facing regions. Each one of these two portions of the enclosure coaxially accommodates a substantially frustum-shaped shaft having, on its lateral surface, a screw which is inscribed in the corresponding portion of the enclosure and protrudes, with its turns, between the turns of the screw of the contiguous shaft. These presses, though their high pressing efficiency, have the drawback that their installation requires considerable space, which is not always available in the plants in which these presses are to be installed.

[0003] Vertical presses are also known which are substantially constituted by a substantially cylindrical enclosure which has a vertical axis and inside which a frustum-shaped shaft is arranged which has, on its lateral surface, a discontinuous screw which is inscribed in the cylindrical enclosure.

[0004] At the upper end of the enclosure there is provided an inlet for the product to be dehydrated, and proximate to the lower end of the enclosure there are outlets for discharging the liquid content of the product that drips from the perforated side walls of the cylindrical enclosure and other outlets for discharging the dehydrated pulp, which is propelled, through the rotation of the frustum-shaped shaft about its own axis, toward the lower end of the enclosure.

[0005] In these presses there is the problem of avoiding as much as possible rotation of the product together with the shaft. This rotation, by reducing the advancement of the product in an axial direction, in fact reduces the effectiveness of the pressing action.

[0006] In order to solve this problem, vanes are fixed to the internal surface of the enclosure and are interposed between the turns of the screw of the shaft so as to contrast as much as possible the rotation of the product.

[0007] Despite this refinement, pressing effectiveness in vertical presses is distinctly lower than in horizontal presses, since the product, despite the presence of the vanes fixed to the internal surface of the enclosure, still has a rotational component in its motion.

[0008] For this reason, in order to increase pressing effectiveness, the products to be processed inside vertical presses receive the addition of adapted chemical substances which facilitate the release of liquids by the product but lead to a contamination of the processed product.

[0009] Moreover, the presence of the vanes on the internal surface of the enclosure produces an unwanted fragmentation of the pulp of the product, which can lead to the release of dust during subsequent drying, forcing the adoption of suitable filtration systems in order to reduce as much as possible the losses of material and limit environmental pollution.

[0010] Another problem that can be observed in currently commercially available vertical presses is related to higher energy consumption, mainly due to the high resistance to the rotary motion of the shaft caused by the presence of the vanes on the internal surface of the enclosure.

[0011] The aim of the present invention is to solve the above problems, by providing a vertical screw-feeder press for dehydrating liquid-containing products, which can have a pressing efficiency which can be compared to the efficiency of horizontal presses.

[0012] Within the scope of this aim, an object of the present invention is to provide a vertical press which considerably limits the fragmentation of the product during pressing, so as to considerably reduce dust production during the process for drying the dehydrated pulps.

[0013] Another object of the present invention is to provide a vertical press whose energy consumption is lower than that of current vertical presses.

[0014] Another object of the present invention is to provide a vertical press which has a high pressing effectiveness without necessarily requiring to add chemical additives to the product during pressing.

[0015] This aim, these objects and others which will become apparent hereinafter are achieved by a vertical screw-feeder press for dehydrating liquid-containing products, characterized in that it comprises an enclosure which is composed of two side-by-side portions which form two substantially conical surfaces which have vertical axes and mutually intersect with their mutually facing regions, each one of said two portions coaxially accommodating a substantially frustum-shaped shaft having, on its lateral surface, a screw which is inscribed in the corresponding portion of the enclosure and protrudes, with its turns, between the turns of the screw of the contiguous shaft; said enclosure having, proximate to the larger-diameter end of said two portions, an inlet for introducing products to be dehydrated in said enclosure and, proximate to the opposite end, at least one outlet for discharging the dehydrated product.

[0016] Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of the press according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

Figure 1 is a schematic partially sectional side elevation view of the press according to the invention;

Figure 2 is an enlarged-scale view of a detail of Figure 1;

Figure 3 is an enlarged-scale sectional view of Figure 1, taken along the plane III-III;

Figure 4 is an enlarged-scale sectional view of Figure 1, taken along the plane IV-IV;

Figure 5 is an enlarged-scale sectional view of Figure 1, taken along the plane V-V.

[0017] With reference to the above figures, the press according to the invention, generally designated by the reference numeral 1, comprises a footing 2 which supports an enclosure 3 composed of two side-by-side portions 4 and 5 which form two substantially conical surfaces which have vertical axes and mutually intersect with their mutually facing regions. Each one of said two portions 4 and 5 accommodates a substantially frustum-shaped shaft 6 and 7 which has, on its lateral surface, a screw 8 and 9 which is inscribed in the conical surface of the corresponding portion 4 and 5 of the enclosure 3 and protrudes, with its turns, between the turns of the screw of the contiguous shaft.

[0018] At the larger-diameter end of the portions 4 and 5, the enclosure 3 has an inlet 10 for introducing the products to be dehydrated; proximate to the opposite end, said enclosure has at least one outlet 11 for discharging the dehydrated product.

[0019] More particularly, the portions 4 and 5 of the enclosure 3 preferably have a cage-shaped structure, so as to allow the liquid component of the product pressed inside said portions 4 and 5 to escape.

[0020] Around the portions 4 and 5, the enclosure 3 is provided with a jacket 12 which laterally delimits a chamber 13 for collecting the liquid component of the product which runs all around the portions 4 and 5.

[0021] The chamber 13 is delimited by a wall 18 in a downward region, and proximate to the bottom of the chamber 13 there are provided outlets 19 for externally discharging the pressed liquid that drips from the side walls of the portions 4 and 5 of the enclosure 3.

[0022] The portions 4 and 5 of the enclosure 3 gradually taper from the top downward, while the diameter of the shafts 6 and 7 gradually increases from the top downward.

[0023] The screws 8 and 9 have a height which gradually decreases from the top downward, so that their outer edge remains adjacent to the internal surface of the portions 4 and 5.

[0024] In this manner a passage section is obtained which gradually decreases from the top downward for the product fed through the inlet 10.

[0025] The shafts 6 and 7 are supported, so that they can rotate about their respective axes, proximate to their upper end, by arms 15 which are fixed to the upper portion of the enclosure 3 and are supported, proximate to their lower end, by a plate 14 which is substantially horizontal and delimits the enclosure 3 in a downward region and is fixed to the footing 2.

[0026] Moreover, the shafts 6 and 7 have, proximate to their upper end, a plurality of vanes 16 which have a variable inclination and are rigidly coupled to said shafts 6 and 7 in rotating about respective axes in order to produce a uniform distribution of the product to be dehydrated, fed through the inlet 10.

[0027] The shafts 6 and 7 can be hollow and can have a plurality of perforations on their side walls so as to allow the passage, inside said shafts 6 and 7, of the liquid fraction of the product being pressed. Said liquid fraction, which flows inside the shafts 6 and 7, can be discharged through a discharge outlet provided at the lower end of the shafts 6 and 7.

[0028] In the plate 14 there are provided two openings 11 for discharging the dehydrated pulp.

[0029] The footing 2 accommodates gearmotors 20 which are connected to the lower end of the shafts 6 and 7 for actuating said shafts 6 and 7 with a rotary motion about their respective axes and with mutually opposite directions of rotation.

[0030] The operation of the press according to the invention is as follows.

[0031] The product to be dehydrated is fed into the portions 4 and 5 of the enclosure 3 through the inlet 10.

[0032] The rotation of the shafts 6 and 7 produces the gradual downward advancement of the product which, following the reduction in the passage section caused by the particular shape of the portions 4 and 5 of the enclosure 3 and of the shafts 6 and 7, is subjected to rising pressing pressures.

[0033] The liquid component of the product exits through the side walls of the portions 4 and 5 of the enclosure 3 and flows along the chamber 13 to the vicinity of the bottom of said chamber, where it is discharged externally through the outlets 19.

[0034] If the shafts 6 and 7 are hollow and perforated on their side wall, part of the liquid fraction of the product flows inside the shafts and is discharged externally at the lower end of said shafts 6 and 7.

[0035] The dehydrated pulp instead flows downward and is discharged through the openings 11 formed in the plate 14.

[0036] It should be noted that the portions 4 and 5 can be provided without lateral perforations. In this case, the liquid component of the pressed product simply flows inside the shafts 6 and 7.

[0037] Since on the inside walls of the enclosure 3 that face the turns 8 and 9 of the shafts 6 and 7 there are no vanes which might hinder the rotary motion of the shafts 6 and 7, a high reduction in energy consumption for actuating the shafts 6 and 7 with a rotary motion about their respective axes is achieved.

[0038] The particular geometry of the portions 4 and 5, of the shafts 6 and 7 and of the screws 8 and 9 effectively avoids rotation of the product during pressing and allows to achieve high pressing pressures, which provide a high efficiency, such as to ensure optimum pressing of the product even without using chemical additives meant to facilitate the release of liquids by the product.

[0039] In practice it has been observed that the press according to the invention fully achieves the intended aim and objects, since it allows to achieve pressing pressures and therefore a pressing efficiency which are comparable with those obtainable with horizontal presses.

[0040] Another advantage of the press according to the invention is that it does not produce pulp fragmentation and therefore significantly reduces the problems related to the disposal of residues during the drying of the dehydrated pulps.

[0041] The press thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may also be replaced with other technically equivalent elements.

[0042] In practice, the materials employed, as well as the dimensions, may be any according to requirements and to the state of the art.

[0043] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A vertical screw-feeder press for dehydrating liquid-containing products, characterized in that it comprises an enclosure which is composed of two side-by-side portions which form two substantially conical surfaces which have vertical axes and mutually intersect with their mutually facing regions, each one of said two portions coaxially accommodating a substantially frustum-shaped shaft which has, on its lateral surface, a screw which is inscribed in the corresponding portion of the enclosure and protrudes, with its turns, between the turns of the screw of the contiguous shaft; said enclosure having, proximate to the larger-diameter end of said two portions, an inlet for introducing products to be dehydrated in said enclosure and, proximate to the opposite end, at least one outlet for discharging the dehydrated product.

2. The press according to claim 1, characterized in that said portions of the enclosure have a cross-section which decreases from the top downward and said shafts have a transverse cross-section which increases from the top downward.

3. The press according to claim 1, characterized in that said portions of the enclosure have a cage-shaped structure in order to allow the lateral escape of the pressing liquid.

4. The press according to one or more of the preceding claims, characterized in that said enclosure comprises, around said conical portions, a jacket which laterally delimits a chamber for collecting the pressed liquid, said chamber being closed in a downward region by a wall and having, proximate to its lower end, at least one lateral outlet for discharging the pressed liquid.

5. The press according to one or more of the preceding claims, characterized in that said shafts are hollow and have perforations on their side walls for collecting the pressed liquid inside said shafts; the lower end of said shafts having an outlet for discharging the pressed liquid.

6. The press according to one or more of the preceding claims, characterized in that proximate to the upper end of the shafts there are provided radial vanes which can be orientated for distributing the product to be dehydrated which is fed through said inlet.

7. The press according to one or more of the preceding claims, characterized in that said at least one outlet for discharging the dehydrated product comprises two discharge outlets formed in a plate which delimits said enclosure in a downward region.

8. The press according to one or more of the preceding claims, characterized in that said shafts are connected, with their lower ends, to gearmotors which are accommodated in the footing of said enclosure below said plate; said gearmotors being actuatable for the rotation of said shafts in mutually opposite directions of rotation about their respective axes.

Drawing